1. The Field of the Invention
The present invention is directed to systems, apparatus, and methods for remediating explosives. More particularly, the present invention is directed to the remediation of explosives which have not detonated.
2. Background Art
Explosive charges are inherently dangerous in a number of respects. Inadvertent detonation poses risks of severe personal injury or death, as well as of substantial property destruction and consequential losses. Explosive charges are, in addition, comprised of material substances, which, even when not consolidated in a shape capable of performing as a detonatable explosive charge, may be toxic and thus potentially injurious to human health and to complex as well as simple plant and animal life.
Explosive charges that are not securely stored in a supervised manner, or isolated from the environment and from indiscriminate access by human and animal life forms, thus present both safety and environmental hazards.
Such hazards are pointedly apparent where an explosive charge fails to detonate after the explosive charge has been installed for that purpose during activities pertaining to mining, construction, or to seismic surveying. Fortunately, installed explosive charges that do not detonate as planned are usually locatable and often recoverable through the expenditure of reasonable efforts and without safety risks to personnel. On the other hand, there do routinely arise circumstances in which undetonated explosive charges of this type are not recovered or simply cannot be recovered. In such circumstances, there exists a risk that the undetonated explosive charge could at some subsequent time be detonated inadvertently or become a source of potentially harmful contaminants.
As an example, seismic survey data used to ascertain the nature of subsurface ground structures is routinely obtained by recording and analyzing shock waves that are propagated into the ground and produced by detonating explosive charges. The shock waves are then monitored during transmission through the ground. In this role, such seismic charges are usually utilized in large sets, installed as an array of individual seismic charges at widely disbursed locations. The seismic charges are interconnected with detonation equipment for remote detonation, either simultaneously or in sequence.
Seismic charges for such surveys can be detonated either above or below the surface of the ground. In either case, it is not uncommon that at least one of any set of such seismic charges does not detonate as intended. Such failures may be caused by defects in the explosive charge itself, by damage caused during installation, by faulty detonation equipment, or by the failure of personnel in the field to make effective interconnections between that detonation equipment and each seismic charge in the installed set.
When a seismic charge installed above the ground fails to detonate as intended, it is usually possible to locate and safely recover the undetonated seismic charge. Nonetheless, circumstances do exist where the detonation of a set of seismic charges installed above the ground dislocates one of the undetonated seismic charges in the set, directing that undetonated seismic charge into a terrain in which the charge cannot be located or cannot be recovered easily. Responsible seismic crews naturally are trained to exercise all reasonable efforts to recover undetonated seismic charges that are located on the surface of the ground, but even the most rigorously indoctrinated and enthusiastic seismic personnel cannot guarantee that all undetonated seismic charges installed above the ground are ultimately recovered.
Aside from the human factor involved, the intervention of severe weather conditions, such as sandstorms, blizzards, tornadoes, or hurricanes, can impede efforts to recover undetonated seismic explosives. Some such weather conditions offer the prospect of even altering the terrain, thereby burying the undetonated seismic charge temporarily or for a substantial duration. Floods can cover the seismic survey site, removing or obscuring undetonated seismic charges. In the extreme, geological surface changes, such as mudslides, rockfalls, and fissures caused by earthquakes, by heavy weather, or even by seismic survey activity itself, can preclude the recovery of undetonated seismic charges, and even obscure the understanding that any seismic charge has failed to detonate.
The safety risk and environmental hazards posed by loose, undetonated explosive charges will be present where any undetonated seismic charge remains uncovered after the detonation of the set of seismic charges of which it was part.
The likelihood that an undetonated seismic charge will be abandoned is greatest, however, relative to the conduct of seismic survey activity based on the detonation of seismic charges installed below the surface of the ground. In such sub-surface seismic detonation activity, a series of deep boreholes is drilled into the earth or rock at predetermined locations that are intended to maximize the data to be derived from the shock waves promulgated from the detonation of the seismic charges. A seismic charge is placed at the bottom of each borehole and then shut in the borehole in a relatively permanent manner using a concrete or a sealing compound, such as bentonite. The balance of the borehole is then backfilled with loose soil and rock, a process which alone accounts for the majority of failed seismic detonations. Backfill materials have an understandable tendency to break the detonating cord leg wires or non-electric transmission line that interconnects the installed seismic charge at the bottom of the borehole with detonating equipment located above the ground. If a seismic charge installed below the ground fails to detonate, the easy removal of the undetonated seismic charge is seriously impeded by yards of backfill and the cured concrete or sealing compound in which the seismic charge was embedded at the bottom of the original borehole. Removing such an installed seismic charge by reexcavating the original borehole or by digging around the original borehole to avoid the sealing compound is extremely laborious and time consuming, potentially unsafe, and in many circumstances virtually impossible.
Thus, in conducting seismic survey activities, particularly seismic survey activities involving the detonation of seismic charges below the surface of the ground, undetonated seismic charges are regularly abandoned in the field. Frequently, even the precise location of undetonated seismic charges cannot be pinpointed. The risks from undetonated explosive charges installed in the ground endure for a substantial time, usually exceeding the durability of ground surface warning signs, fencing, or the continued possession and control of access to the site by an original owner. Eventually, the pressure of human population growth may render the site attractive for civil or industrial activities that would not be consistent with buried undetonated explosive charges.
The associated dangers include first that of an accidental detonation at some future time. Less dramatic, but certainly of longer duration, are risks presented by the material substance of those undetonated charges. Once released from the confines of the casing of an explosive assembly, the explosive material therein may cease to present any risk of explosion. This type of release of explosive materials can occur through corrosion of the casing through the action of ground water, the fracture of the casing during careless installation, or the shifting of the ground structure at the location at which the undetonated seismic charge was abandoned. In due course, the prolonged effect of these forces in combination with surface erosion or subsurface fluid migration can disburse over a large area the material of a fractured explosive charge. That material may constitute a potentially problematic contaminant. Even if detected, remedial activities may be required to contain and possibly eliminate the contaminant.
Nonetheless, no practical methods exist for reliably remediating the risks posed by undetonated explosive charges, particularly where those undetonated explosive charges are originally installed below the surface of the ground.
It is thus the broad object of the present invention to protect public health and safety from risks arising from incidents of abandoned undetonated explosive charges.
Accordingly, it is a related object of the present invention to eliminate the possibility of detonation of abandoned explosive charges.
It is a complementary object of the present invention to reduce the likelihood that abandoned undetonated explosive charges will contribute to environmental pollution.
Thus, it is a specific object of the present invention to provide apparatus, systems, and methods for remediating in situ any installed explosive charge that fails to detonate as intended.
It is a particular object of the present invention to provide such apparatus, systems, and methods as are capable of reliably and safely remediating an undetonated explosive charge abandoned in the ground.
Yet a further object of the present invention is to provide such apparatus, systems, and methods as are capable of remediating an undetonated explosive charge, even if the location of the explosive charge cannot be ascertained with any degree of certainty.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or will be appreciated by the practice of the invention.
To achieve the foregoing objects, and in accordance with the invention as embodied and broadly described herein, apparatus, systems, mixtures and methods are provided that remediate in situ an undetonated explosive utilizing the biological activity of microorganisms.
In one form, an apparatus incorporating teachings of the present invention includes a quantity of explosive material and microorganisms that is disposed in sufficient proximity to the quantity of the explosive material that the microorganisms can initiate bioremediation of the explosive material when the microorganisms are mobile. Similarly, an explosive mixture is formed by intermixing the microorganisms and the explosive material, which, when hydrated, activates the microorganisms to initiate bioremediation of the explosive material. The explosive apparatus preferably has a shell that enables water to flow through the shell to contact the explosive material. The shell may, for example, have an open end, have holes or be water permeable.
The apparatus or mixture may also further comprise a mobilization means for mobilizing the microorganism to contact the explosive material. The mobilization means enables the microorganisms to initiate bioremediation of the explosive material or to continue bioremediating the explosive material. The terms xe2x80x9cmobilexe2x80x9d and xe2x80x9cmobilityxe2x80x9d refer to the ability of the microorganisms to move, to be activated or made xe2x80x9cactive,xe2x80x9d to be carried by the movement of a liquid, to be distributed to the explosive material or to be unrestricted in movement by a barrier that, previously confined the microorganisms such that after the barrier is removed, the microorganisms can contact the explosive material. The term xe2x80x9cactivexe2x80x9d refers to the state of the microorganisms wherein the microorganisms can bioremediate explosives.
An example of a mobilization means that is useful with an explosive apparatus or an explosive mixture includes a water-permeable container that enables water to contact the explosive material and microorganisms therein, and the addition of a porous material, such as foamed cellulose and/or starch, to the cast explosive to permit passage of moisture therethrough.
The microorganisms can be mobile or deactivated. Examples of deactivated microorganisms that typically require activation include microorganisms that have been dehydrated by air drying or through lyophilization. The microorganisms are preferably freeze dried to increase the survivability of the microorganisms during the forming process wherein the explosive material and microorganisms are combined. More specifically, it is desirable to heat the explosive material to increase the moldability of the explosive material and to enable the microorganisms and explosive material to be easily intermixed. However, the heat can be lethal to the microorganisms as the microorganisms are placed or mixed in the explosive material. Accordingly, the microorganisms have preferably been prepared such that the microorganisms are sufficiently resistant to heat that a significant portion of the microorganisms survive the intermixing or placement process even when the process occurs at a temperature of about 100xc2x0 C. Alternatively, the microorganisms can be incorporated within or on the surface of a foam material that acts as an insulator which protect microbes and nutrients from thermal damage.
The microorganisms can be disposed in close proximity to the explosive material or dispersed within the explosive material in many different forms. The microorganisms can be in various aggregations such as in chips, in or on foamed materials, and in or on porous materials. The aggregations can also be added without any processing of the microorganisms to form the microorganisms into a particular distinct form. Accordingly, the microorganisms can be present as a flake, granule, clump, powder or shard of a nutrient medium containing microorganisms. In a preferred embodiment, the microorganisms can be contained within one or more chips. More particularly, each chip can additionally include cellulose therein, the cellulose expanding upon contact with moisture to cause cracking of the chip and the cast explosive matrix, which contributes to the mobility of microorganisms.
Nutrients, in addition to the explosive material, are generally necessary for the microorganisms to survive and grow. A nutrient is any substance that provides nourishment to the microorganism, such as a mixture of trace nutrients or elements, and/or any substance providing a source of carbon, nitrogen, and phosphate. In a preferred embodiment of the invention, dispersal of casamino acids provides nourishment to the microorganisms and accelerates microorganism growth subsequent to a failed detonation. Binders are also often necessary and organic binders are preferred. Depending on the binder or nutrient utilized, one chemical can perform the function of both binder and nutrient. The thermal resistance of the microorganisms can also be increased by utilizing various thermal protection additives.
Ideally, the remediation occurs in two respects. The explosive is disabled from inadvertent detonation. Subsequently, the material composition of the explosive material is rendered relatively nonharmful.
In another embodiment of the invention, microorganisms are releasably contained by gelatin, a substance that is self-effacing when contacted by microorganisms under favorable conditions.
In yet another embodiment, microorganisms are applied directly to the exterior of the explosive material or to the shell of an explosive apparatus.